Pressure-responsive switch



Feb. 28., 1967 l E, QGOODWIN 3,306,999

PRESSURE-RESPONSIVE SWITCH 2 Sheets-Sheet 1 Filed 001:. 5, 1964 22 3 Figi INVENTOR. JOE E. GOODWIN ATTORNEY Feb. 28, 1967 J. E. GOODWINPRESSURE-RESPONSIVE SWITCH 2 Sheets-Sheet 2 Filed Oct. 5, 1964 Fig 7INVENTOR. JOE E. GOODWIN ATTORNEY United States Patent Office 3,306,999PRESSURE-RESPONSIVE SWITCH Joe E. Goodwin, Houston, Tex., assignor toSentinel Distributors, Inc., Denver, Colo., a corporation of DelawareFiled on. s, 1964, Ser. No. 401,429 5 Claims. c1.20n s2 The instantinvention relates to a pressure-responsive switch employableautomatically to sense and protectively apply deficiences of pressuremanifest in fluid circulation systems significant to the normaloperation of mechanical equipment, and has as its principal object theprovision of a novel and improved such unit of diverse applicability andoperatve reliability.

, A further object of the invention is to provide a novel and improvedpressure-responsive switch that is dependably effective to interruptoperation of associated equipment in immediate reaction to loss ofrequisite pressure in a fluid circulating system consequential to properfunctioning of the equipment.

A further object of the invention is to provide a novel and improvedpressure-responsive switch that is efficiently applicable to immediatelyand automatically reflect loss of requisite pressure in a fluidcirculating system primary to proper functioning of mechanical equipmentthrough either alternative or simultaneous interruption of equipmentoperation, actuation of alarms and signals, and activation of adjunctiveprotective and corrective facilities.

A further object of the invention is to provide a novel and improvedpressure-responsive switch incoroprating means readily facilitatingcorrection of conditions signaled by automatic reaction of the switch.

A further object of the invention is to provide a novel and improvedpressure-responsive switch adapted automatically to close for completionof an electrical circuit in reaction to loss of requisite pressure in anassociated fluid circulating system and automatically to open to a resetcondition of potential use upon re-establishment of requisite pressurein the system.

A further object of the invention is to provide a novel and improvedpressure-responsive switch adapted automatically to close for completionof single or multiple electrical circuits in reaction to loss ofrequisite pressure in an associated fluid circulating system,automatically to a reset condition of potential use uponre-establishment of requisite pressure in the system, and to accommodatemanual interruption of the circuit or circuits there- 'by closedincident to correction of the conditions signaled by closing of theswitch.

A further object of the invention is to provide a novel and improvedpressure-responsive switch that is particularly adapted for intended usewith isolated unattended equipment installations exposed to weather andtherewith rugged and dependable in attainment of its functions.

A further object of the invention is to provide'a novel and improvedconstruction and operative interrelation of features and elements in andas a pressure-responsive switch applicable to inhibit damage toelectrically governed, mechanical equipment consequential to loss ofrequisite pressure in an associated fluid circulating systern.

A further object of the invention is to provide a novel and improvedpressure-responsive switch that is expedient and economical ofproduction, simple and convenient of operative installation, feasible ofadaptation for operative reaction to pressure values selected from anextensive available range, reliably indicative of pressure deficienciesrequiring attention, suited for repetitious functioning 3,306,999Patented Feb. 28, 1967 under corrected conditions without occasion forreplace,- ment, servicing, or maintenance, substantially immune toadverse effect by climatic environment or the extremes of weathervariations, and positive and efficient in attainment of the ends forwhich designed. p

In broad functioned analogy, the present invention is employable incombination with, as a supplement to or as a substitute for a switchdevice disclosed in United States Patent No. 3,082,306 dated March 19,1963.

With theforegoing and other objects in view, my invention consists inthe construction, arrangement, and operative combination of elements andfeatures as hereinafter set forth, pointed out in the appended claims,and illustrated by the accompanying drawings, in which:

FIGURE 1 is a vertical section taken substantially axially through atypical, simple embodiment of the invention as associated with a fluidpressure line and an electrical conductor in condition of potential use,the position of the illustrated elements reflecting a state of requisitepressure obtaining within the system represented by the pressure line.

FIGURE 2 is a top view of the arrangement according to FIGURE 1 withcertain exterior attachment broken away to conserve space.

FIGURE 3 is a vertical, substantially-axial section through thearrangement according to the preceding views taken at a right angle tothe showing of FIGURE 1 approximately on the indicated line 33 of FIGURE2.

FIGURE 4 is a fragmentary, detail, transverse section, on arelatively-enlarged scale, taken approximately on the indicated line 44of FIGURE 3.

FIGURE 5 is a side elevational view, partly in vertical, axial section,of a multi-circuit elaboration of the organization according to thepreceding views within the contemplation and effective to apply theprinciples of the invention. I

FIGURE 6 is a top plan view of the arrangement according to FIGURE 5with certain of the exterior attachments broken away to conserve space.

FIGURE 7 is a partial side elevation showing the upper portion of thearrangement according to FIGURE 5 as viewed from the indicated line 7-7of FIGURE 6 with a housing component in diametric section to exposeotherwise concealed associations. 7

FIGURE 8 is a side elevation of the upper portion of the arrangementaccording to FIGURE 5 showing through an opened area of the housingcomponent the element relationships obtaining upon actuation of theswitch occasioned by loss of requisite'pressureinthe associated pressureline.

It is common experience in the operation of internal combustion engines,powered pumps, compressors and analogous mechanical apparatus, howevercooled and lubricated, that decline of normal operating pressure in anassociated fluid circulating system, such as the lubricating oilcircuit, may develop to induce overheating of the operating mechanismswhich, if not observed and promptly countered, promotes damage to andpossible destruction of the equipment with concomitant interruption ofthe ofttimes critical functions thereof. Technical advances in manyfields and services have aggravated the problems and consequences ofequipment failure due to inadequate fluid circulating pressures becauseof the expanding practice of locating powered equipment installationsremote from observation and prompt access to operate, eithercontinuously or intermittently,,without attention for long periods oftime subject to malfunction promotive of or consequent upon inadequatepressure of fluid circulation. Previous recognition of the unpredictablepossibility of such malfunctions has hitherto occasioned the provisionof means effective in exposure and reaction to the variable operatingconditions of a given-equipment installation to halt the action thereofin automatic response to loss of requisite fluid circulating pressurebefore serious damage ensues. Commonly applied to control the efficacyof an electrical circuit governing operation of the associatedequipment, the pressure-responsive means hitherto available for thepurpose discussed have been less than satisfactory by reason ofstructural complexity, indurability, especially when exposed to Weather,over-sensitivity, expense, vulnerability as attractive targets forgunners, lack of resetting facility, and inadequate practicalreliability, in correction of all of which the instant invention isdirected to the provision of a novel and improved pressure-responsiveswitch diversely applicable in appropriate association with fluidcirculating systems to positively and dependably close an electricalcircuit controlling operaton of the associated equipment and, ifdesired, to energize other electrical circuits whereby to signal orextend the effect of such action, at a predetermined reduction ofrequisite pressure in the fluid circulating system whereto applied.

Manifestly adapted to function as intended in practical association withequipment of many different types, constructions, and capabilitiesutilizing fluid circulating systems subject to loss of pressurerequisite to sustain efficient operation thereof, the improved switch ofthe invention is constituted as a rugged, unitary assembly integratedwith an upon a preferably-cylindrical body of appropriate size andsuitable rigid material furnished with an exterior bracket attachment 11of optional particularity ernployable to securely mount said body 1%with its axis .uprightin any selected use location. A through borelongitudinally traverses the body 10 to define therein a cylindricalchamber 12 adjacent and accessible through the lower end of the body anda tubular cavity 13 coaxially communicating in a lesser diameter withand 'as an uprise fromsaid chamber. The lesser diameter of the cavity'13 may open directly to the chamber or may, as illustarted, communicatewiththechamber through a counterbore '14 formed to a diameter betweenthose ofthe chamber and cavity.

The body 10 reciprocably houses an actuator 15 having a piston component16 receivable in sliding coaction within .the chamber 12 and a coaxialstem component 17 receivable in sliding coaction within the cavity 13,the conjunction of said piston and stem components being marked, ifdesired, by a stepped boss 18 suited for sliding reception'within thecounterbore 14. In appropriate relative axial lengths qualifying theactuator with an adequate range of playwithin and relative to itshousing, the piston component 1-6 is slidablysealed to its chamber by anO-ring 19, or the equivalent, and the stem component 17' iscorrespondingly slidably sealed to its cavity by an O-ring 20, or theequivalent, whereby to establish between said seals 19 and 20 an uppercornpartmento-f the chamber 12 conditioned to effectively confine fluidunder pressure for reaction directly upon the contiguous area of thepiston component 16. Where it opens through the lower endof the body Ifthe chamber 1-2 is stepped to receive and seat a flat, annular endclosure 21 formed with a vent aperture 22 and detachably retained inoperative disposition by means of a snap ring'23 conventionallygroove-seated in the body exteriorly there against. Fixed relative tothe body 10, the end closure21 serves as an abutment for one end of anexpansive spring 24 hearing within the lower portion of the chamber 12against the actuator 15 and hence effective to urge the latter to theupper limit of its reci'procable range within the body, it beingexpedient, as illustrated, to accommodate the upper end of the springwithin a socket formed to open through the lower face of the piston 16,whereby to facilitate interchange of the spring element and usetherewith of adapters applicable to vary and determine the expansiveforce acting upon the actuator.

The actuator-biasing influence of the spring 24 is directly opposed tothe pressure of fluid circulation whereto the switch of the presentinvention is designed to react, for which purpose the fluid circulationto be pressure-sensed is directed through the upper compartment of thechamber 12 operatively detfined between the seals 19 and 20 by meansof'a flow input line 25 opening in communication with the fluidcirculation system of the equipment to be protected through the body 10to'said chamber above the upper limiting position of the piston 16 and acomplementary flow output line 26 similarly communicating as a return tosaid system from said chamber compaitment, the full pressure of fluidcirculation in the associated system being reflected and maintained insaid chamber to oppose through the actuator the proportioned influenceof the spring 24 in consequence of a flow capacity for the output line26 reduced, as at 27, relative to that of the input line 25. As soorganized and connected in position of intended use with a biasing valuefor the spring 24 less than the force of requisite fluid pressure actingon the upper area of the piston 16, appropriate pressure of fluidcirculation depresses and holds the actuator 15 against the influence ofthe spring which, in reaction to decrease in the pressure of thecirculating fluid, immediately and automatically acts to elevate theactuator relative to and within the body 10.

Reciprocatory displacement of the actuator 15 responsive to the biasingand pressure influences as above described is availed of to operatecontrols of preferred particularity andequipment-protectingsignificance. De signed and effective to halt the functioning ofelectricallygoverned equipment in reaction to inadequate pressure offluid circulation sensed thereby, the embodiment of the invention.represented by FIGURES 1-4, inclusive, of the drawings is arrangedtoclose a single-lead circuit thereby qualified, in any desired conformitywith known practice, to interrupt operation of the associated equipment. Given, as is quite customary, a single-lead control circuittypified by the fragmentary showing ofa conductor 28 'amenabletocompletionat ground 29 on the associated equipment with concomitantinterruption of equipment operation, it is feasible and expedient toform the elements 10, 11', 15, .21 and'24 of conductive material suitedin their structural interrelation as set forth to pass current totheground 29. .In such an arrangement, the con ductor 28 closes from theinstrumentalities to be actuated by theclose'd circuit to a connection30 exteriorly of the upper end of the body'lti which serves in closing,in- 1 s'uiated relation With the upperend of the body cavity 13 acontact 31'the'rc'by fixed within said cavity in spaced I opposition tothe upper endof the actuator stem 1'7,

and a coaxial pin extension 32 of conductive material is provided atsaid upper end of. the stern 1'7 in a length adapted to engage saidcontact 31 with circuit-closing effect when the influence of the spring24 prevails to elevate the actuator 16 against the pressure of fluidcirculation manifest in the upper compartment of the chamber Hand toseparate from said contact and open the circuit when the fluid pressureis dominant to depress the actuator against the force of the spring.Thus, as should be readily apparent, the switch organization accordingto FIGURES l4, inclusive, reliably functions without impairment ofnormal equipment operation to automatically arrest such operation whenthe pressure of fluid circulation requisite thereto is incapable ofdominating through the piston 16 the pre-proportioned influence of. thespring 24.

Intentional resumption of equipment operation at adequate pressure offluid circulation, once appropriately initiated, will quite naturallyreset the switch of the invention for repetitious intended functioningas the adequate fluid pressure dominates the influence of the spring 24,and interruption of the circuit typified by the.

conductor 28 to condition the. equipine'nt'for resumed operation may bevariously accomplished, as is obvious. However, considerations ofconvenienceand practicality recommend the provisionof amanually-actuable reset device capable as a component'of' the switchassembly unit of separating the pin 32 from the contact 31 pre liminaryto resumption'of .the equipment operation'inten r-upted by circuitcompletion therethrough, and such a reset device is represented in theviews of the drawings as an optional supplement to' the functionalswitch organization hereinbefore described. As best shown in FIG- URES3, 4 and S, the reset device is constituted as a bolt 33 axiallyreciprocablethrough a wall of the body radially of the actuator, tointrusion within the body cavity 13. In a length exceeding thethicknessof the body wall thereby traversed the bolt 33 terminates in an enlargedhead 34 exteriorly of'the body against which an expensive spring 35socketed in the body wall acts to yieldably urge the bolt outwardly ofthe body to a limiting position determined'by a stop 36 fixed in thebody 10 perpendicular to the bolt and through a slot 37 longitudinallythereof, whereby to normally retain the bolt under outward bias with itsinner end substantially tan-gent to the wall of the body cavity 13 andamenable to intrusion there Within. The conjunction of the actuator stem17 and its pin 32 is formed as an annular, preferably frusto-conical,shoulder 38 and the inner end of the bolt 33 is complementarilycharnfered, as at 39, so that, the said bolt being located axially ofthe actuator 15 and cavity 13 to effect sliding coaction of itschamfered end 39 with the shoulder 38 when the actuator is elevated toengagement of the pin 32 with the contact 31, inward displacement of thebolt occasions interengagement of the shoulder 38 and chamfered boltnose 3-9 with consequent depression of the actuator 15 against theinfluence of the spring 24 sufficient to retract the pin 32 from thecontact 3'1 for interruption of the circuit completed therethrough. Witha fluid pressure in the chamber 12 in adequate to dominate the influenceof the spring 24 the friction attending interengagernent of the shoulder38 and bolt nose 39 suffices to retain the bolt in itscircuitin-terrupting inward displacement against the bias of its spring35 until corrective measures justify resumption of equipment operationand further retraction of the actuator in reaction to requisite fluidpressure manifest in the chamber 12, whereupon the spning 35automatically retracts the bolt 33 from intrusion within the body cavity13 to reassociate the elements of the switch assembly for intended use.

The elaboration of the invention represented by FIG- URES 5-8,inclusive, of the drawings differs from the foregoing but in the meansresponsive with circuit-closing eifect to elevation of the actuator 15incident to drop of fluid pressure manifest in the chamber 12 andincludes in equivalent structure, correlation, and mode of operation theelements and features heretofore described with the exception of theground 29 and contact 31. In an arrangement operable automatically toenergize and complete warning, signaling and analogous circuits, whendesired, in addition to a circuit controlling equipment operation, thebody 10 of the previous disclosure is formed with a prolongation 40fixedly outstanding axially therefrom at one side of the open upper endof the body cavity 13 and a conventional, multi-circuit, micro'switchunit 41 housing, as is customary, a detent yieldably biased toopen-circuit condition and rockable by an exposed projection 42 toclosed-circuit condition is secured to said prolongation 40 spacedlyabove and in overhanging relation with the open upper end of the bodycavity 13 in such disposition as to direct the projection 42 as biasedto open-circuit condition toward the body 10 at one side of said cavity.A flexible finger 43 extends from endattachment to the unit 41 over andacross the open end of the cavity 13 to underlie at its free end themicroswitch projection 42, whereby upward flexing of said finger 43applies through said projection to rock the unit detent tocircuit-closing condition, and an elongation of the actuator pin 32,designated 32', is provided in a length suited to engage said fingerbetween its end attachment 'and the projection 42 and flex the fingerfor closing of the detent circuits when the actuator 15 is elevated inreaction to dominance of its spring bias and to retract from said fingerwith concomitant return of the detent to open-circuit condition with theactuator is depressed by dominance of fluid pressure.

The microswitch unit 41 is conventionally furnished with a plurality ofexteriorly-available circuit connections, one of which, designated 44,provides attachment for a powered lead, such as 28 of the earlierdisclosure, and the others of which, 45, serve to complete circuitsthrough leads 46 to the instrumentalities desired to be energized whenthe pressure of fluid circulation is inadequate and receive current fromthe lead 28 upon rocking of the detent to its circuit-closing condition,all of which is well within known skill and practice. The upper end ofthe body It) is worked about the base of the prolongation 40 to receiveand coact by means of a sealing ring 47 with the open end of a capclosure 48 invertible over and to protectively house said prolongationand the microswitch unit 41in a separable association secured by a screw49 engaged through the closed end of the cap closure with the end of theprolongation 40 thereunder. The leads and 28 obviously must intersectand be insulated from the cap closure 45? in some expedient manner, andsuch is readily, conveniently, and conventionally accomplished by theprovision of a binding post 30 for each of the several circuits securedin insulated relation to and to continue the respective circuit throughthe .closed end of the cap closure.

Utility, function, and mode of operation of the organization representedby FIGURES 5-8, inclusive, should be fully apparent from the descriptionof the embodiment first discussed as hereinabove amplified.

Since changes, variations, and modifications in the form, construction,and arrangement of the elements shown and described may be had withoutdeparting from the spirit of my invention, I wish to be understood asbeing limited solely by the scope of the appended claims, rather than byany details of the illustrative showing and foregoing description.

I claim as my invention:

1. A pressure-responsive switch comprising a rigid body formed with athrough bore defining a cylindrical chamber coaxially communicating witha tubular cavity of lesser diameter, an actuator having coaxial pistonand stem components respectively slidably sealed in said chamber andcavity, a chamber end closure at the side of the piston remote from thestem, a spring expansively reactive between said end closure and theproximate side of the piston yieldably biasing the actuator in thedirection of its stem, at fluid flow input line and a relativelyrestricted fluid flow output line serving said chamber between thepiston and stem seals, whereby fluid pressure in said chamber opposesthe influence of said spring and said actuator is moved axially inresponse to a differential in the opposed spring and fluid pressurefactors, an electrical circuit operatively associated with said body, aclosable said 'body and the end of the actuator stem component remotefrom the piston, and a pin extending from said end of the sterncomponent adapted to engage said housing to close said break andcomplete the circuit upon shift of the actuator under dominance ofspring pressure and to open said circuit upon shift of the actuatorunder dominance of fluid pressure.

2. A pressure-responsive switch comprising an actuator reciprocablyhoused within a rigid housing, said actuator having coaxial piston andstem components, said piston component being slideably housed within achamber in said housing and said stern component being slideably breakin said circuit normally open betweenhoused within a tubular cavity insaid housing opening in a lesser diameter to said chamber, a pistoncomponent seal slideably sealing said piston component in coaction withsaid chamber, a stern component seal slideably sealing said stemcomponent within said tubular cavity, means yicldably biasing saidactuator in the direction of its stem component, means for thepressure-circulation of fiuid through said housing between the pistonand stem component seals in opposition to the yieldable biasing meansinfluencing the actuator, said pressure-circulation means including flowinput and flow output lines separately serving the housing chamber atthe stem side of the piston component therein, said flow output linehaving flow communication with the chamber restricted relative to thatof the flow input line thereby positively to reflect within the chamberthe pressure of the flow circulated therethrough, a normally-openelectrical circuit operatively associated with said housing, and meansfor closing said circuit in response to a shift of said actuatoroccasioned by the dominant influence of said yieldable biasing means. I

3. A pressure-responsive switch according to claim 2 wherein the meansyieldably biasing the actuator in the direction of its stern componentcomprises a chamber end closure at the side of the piston componentremote from the stem and an expansive spring reactive between said endclosure and the proximate side of the piston component.

4. A pressure-responsive switch according to claim 2 wherein the housingactuator and associated elements are of conductive material suited tofunction in an electrical circuit, the normally-open circuit associatedwith the housing includes a contact insulated from the housing in spacedopposition to the end of the actuator stem component remote from thepiston, and the means for closing such circuit consists of a conductivepin extension of said end of the stem component adapted to engage saidcontact when the bias influencing the actuator overcomes the pressure offluid circulation and to separate from the contact in a reversedcorrelation of the pressure and bias factors.

5. A pressure-responsive 'switch comprising an actuator reciprocablyhoused within a rigid housing, said actuator having coaxial piston andstem components respectively slideably sealed within said housing, meansyieldably biasing said actuator in the direction of its stern component,means for the pressure-circulation of fluid through said housing betweenthe piston and stem component seals in opposition to the yicldablebiasing means influencing the actuator, the housing actuator and'associated elements being of conductive material suited to function inan electrical circuit, a normally open electrical circuit operativelyassociated with said housing and including a contact insulated from thehousing in spaced opposition to the end of the actuator stem componentremote from the piston, and means for closing said circuit in responseto a shift of said actuator occasioned by the dominant influence of saidyieldable biasing means, said means for closing said circuit comprisinga conductive pin extension of said end of the stem component adapted toen'- gage said contact when the bias influencing the actuator overcomesthe pressure of fluid circulation and to separate from the contact inareversed correlation'of the pressure and bias factors.

References Cited by the Examiner UNITED STATES PATENTS 1,856,584 5/1932Parkhill 200-82 3,077,524 2/1963 Blackburn 200-82 3,077,854 2/1963 Pall116-70 3,171,916 3/1965 Solski et al. 20082 I FOREIGN PATENTS 153,42911/1920 Great Britain.

BERNARD A. GI'LHEANY, Primary Examiner. H. BROOME, G. MAIER, AssistantExaminers.

1. A PRESSURE-RESPONSIVE SWITCH COMPRISING A RIGID BODY FORMED WITH ATHROUGH BORE DEFINING A CYLINDRICAL CHAMBER COAXIALLY COMMUNICATING WITHA TUBULAR CAVITY OF LESSER DIAMETER, AN ACTUATOR HAVING COAXIAL PISTONAND STEM COMPONENTS RESPECTIVELY SLIDABLY SEALED IN SAID CHAMBER ANDCAVITY, A CHAMBER END CLOSURE AT THE SIDE OF THE PISTON REMOTE FROM THESTEM, A SPRING EXPANSIVELY REACTIVE BETWEEN SAID END CLOSURE AND THEPROXIMATE SIDE OF THE PISTON YIELDABLY BIASING THE ACTUATOR IN THEDIRECTION OF ITS STEM, A FLUID FLOW INPUT LINE AND A RELATIVELYRESTRICTED FLUID FLOW OUTPUT LINE SERVING SAID CHAMBER BETWEEN THEPISTON AND STEM SEALS, WHEREBY FLUID PRESSURE IN SAID CHAMBER OPPOSESTHE INFLUENCE OF SAID SPRING AND SAID ACTUATOR IS MOVED AXIALLY INRESPONSE TO A DIFFERENTIAL IN THE OPPOSED SPRING AND FLUID PRESSUREFACTORS, AN ELECTRICAL CIRCUIT OPERATIVELY ASSOCIATED WITH SAID BODY, ACLOSABLE BREAK IN SAID CIRCUIT NORMALLY OPEN BETWEEN SAID BODY AND THEEND OF THE ACTUATOR STEM COMPONENT REMOTE FROM THE PISTON, AND A PINEXTENDING FROM SAID END OF THE STEM COMPONENT ADAPTED TO ENGAGE SAIDHOUSING TO CLOSE SAID BREAK AND COMPLETE THE CIRCUIT UPON SHIFT OF THEACTUATOR UNDER DOMINANCE OF SPRING PRESSURE AND TO OPEN SAID CIRCUITUPON SHIFT OF THE ACTUATOR UNDER DOMINANCE OF FLUID PRESSURE.